A sander is a power tool used to smooth surfaces by abrasion. It typically features a motor that drives a sanding pad or belt, which is covered with sandpaper. Sanding is essential in woodworking and construction to prepare surfaces for finishing, such as painting or varnishing. There are various types of sanders, including the orbital sander, which moves in a circular motion, and the belt sander, which uses a continuous loop of sandpaper. Each type is designed for specific tasks, making them valuable tools for both professionals and DIY enthusiasts in projects involving wood, metal, or plastic.